MRI Correlates of Limb Ischemia in PVD

描述(由申请人提供)： 外周血管疾病(PVD)由吸烟、糖尿病和高血压引起，在65岁以上的人群中，约有10%的人会导致肢体缺血。如果不积极治疗，PVD会导致跛行、组织缺血、坏疽和截肢。由于PVD，每年有9万例截肢手术。目前可用的诊断方法包括侵入性技术，如放射血管造影术，由于造影剂的毒性，这可能会导致严重的并发症，如肾功能衰竭。然而，诊断性医疗机构正在蓬勃发展。如今，双工多普勒和核磁共振血管造影术等非侵入性技术可以在没有放射血管造影术的情况下完成手术，并在选定的人群中取得高度成功。慢性临界肢体缺血(CCLI)患者在接受血管重建或截肢手术时，肢体丧失、围手术期发病率和死亡率的风险最高。有证据表明，目前的诊断方法仍然主要针对识别大血管血流障碍，不能充分帮助外科医生评估CCLI患者的血运重建潜力。因此，在这一人群中，移植的成功率要差得多，导致重复手术，经常推迟截肢，延长康复时间，以及过高的发病率和死亡率。令人惊讶的是，当外科医生预测截肢残端伤口无法愈合时，他们50%的时间是错误的，这让人怀疑他们对截肢合适水平的估计是否有点过于激进。我们提出了一种非侵入性的MRI方法--动脉自旋标记灌注MRI来解决这一问题。动脉自旋标记序列已被开发用于研究小腿和足部的微血管血流。我们打算在高场MRI中进一步发展和应用这项技术，在那里信号和分辨率可能会得到改善。我们还建议开发足部、小腿和前臂的血流指数，并将它们与公认的诊断标准进行比较。最后，我们将前瞻性地应用它们来预测移植物的通畅性和截肢后的伤口愈合。

DESCRIPTION (provided by applicant): Peripheral vascular disease (PVD) caused by smoking, diabetes mellitus, and hypertension, results in limb ischemia in approximately 10% of the population over age 65 years. PVD results in claudication, tissue ischemia, gangrene, and amputation when not treated aggressively. Ninety thousand amputations are performed each year as a result of PVD. Diagnostic methods available at present include invasive techniques such as radiographic angiography, which, because of contrast dye toxicity, can result in serious complications such as renal failure. The diagnostic armamentarium is burgeoning however. Noninvasive techniques such as duplex Doppler and MRI angiography are today allowing surgery to be completed without radiographic angiography and with a high degree of success in selected populations. Patients with Chronic Critical Limb Ischemia (CCLI) are at the highest levels of risk for limb loss and perioperative morbidity and mortality when re-vascularization or amputation is performed. Evidence indicates that current diagnostic methods, again directed primarily at identifying macro-vascular flow impediments, do not adequately assist the surgeon in assessing potential for revascularization in patients with CCLI. As a result, grafting success is much poorer in this population, leading to repeated procedures, often delayed amputation, prolonged rehabilitation, and excessive morbidity and mortality. Astoundingly, when surgeons predicted that amputation stump wounds would not heal, they were wrong 50% of the time, leading one to wonder if their estimation of appropriate level for amputation doesn't tend to be a bit too aggressive. We propose the application of a noninvasive MRI method, Arterial Spin Labeling Perfusion MRI to this problem. Arterial spin-labeling sequences have been developed to study micro-vascular blood flow in the calf and foot. We intend to further the development and application of this technique at high field MRI where improved signal and resolution are likely. We also propose to develop flow indices for the foot, calf, and forearm and compare them with recognized diagnostic standards. Finally, we will apply them prospectively to predict graft patency and wound healing after amputation.